This invention relates to a method and apparatus for load sharing and overload control of packet media gateways under control of a single media gateway controller. More particularly, the invention is directed to a technique for load sharing and overload control implemented by defining an interface between a media gateway (MG) and a media gateway controller (MGC) to handle both general and resource usage and congestion. In addition, a new event strategy is defined that allows for reporting of resource utilization so that the media gateway controller (MGC) can take appropriate action to maximize call completion. Such action may include evenly distributing traffic among available media gateways, smart routing around a congested media gateway or intelligent throttling of traffic based on knowledge of specific resources that are congested.
While the invention is particularly directed to the art of traffic balancing and overload management for media gateways, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the invention may be used in any traffic management technique where it is desirable for a controller to manage traffic in the absence of detailed information on hardware components through which the traffic flows.
By way of background, a typical method by which a media gateway controller determines and manages the resource capacity of a media gateway is to count resources until some provisioned maximum is reached. To do so, the media gateway controller is provisioned to understand the equipment in the media gateway.
However, this type of arrangement is not desirable in all circumstances. It requires that the media gateway controller possess detailed information on hardware components through which the traffic flows. It also requires that the media gateway keep dynamic counters to depict the usage of the hardware components. This type of solution is not robust and requires great effort to keep the counters in synchronization with the real hardware usage. It would be desirable to provide a technique that allows the media gateway controller to operate without explicit knowledge of resource capacity in each media gateway.
The recognized standard for media gateway control, and specifically control of the interface between the media gateway controller and the media gateway, is set forth in ITU-T Recommendation H.248 (June 2000), which is incorporated herein by reference. Currently there exist H.248 (ITU-T Recommendation H.248.10 (July 2001) and ITU-T Recommendation H.248.11 (November 2002)—which are incorporated herein by reference) packages for congestion and overload management. For example, an overload control package defined in H.248.11 is based on a command structure whereby the media gateway (MG) sends Notify commands to the media gateway controller (MGC) in response to Add attempts that are made while the media gateway (MG) is in overload. This approach requires that the media gateway controller (MGC) maintain control algorithms and “leaky bucket” counters to determine throttle percentages based on the state of the counters. This approach generates extra messaging during periods of congestion and only handles general media gateway congestion.
Another approach to resource capacity overload involves setting arbitrary thresholds for reducing traffic problems. For example, a congestion package defined in H.248.10 provides for reporting between the media gateway and the media gateway controller. The media gateway reports to the media gateway controller a predetermined percentage of traffic to throttle, or reject. This approach also only handles general media gateway congestion. Another deficiency of this approach is that it is reactive in nature, only informing the media gateway after there is already a problem.
The present invention contemplates a new and improved system that resolves the above-referenced difficulties and others.